Abstract

Friction spot welding is a kind of solid state welding process which can prevent welding defects observed in fusion welding processes. Friction stir welding inherently utilizes a rotating tool and a keyhole is formed after retreat of the tool like a welding crater. In this paper, two kinds of keyhole refilling techniques (1-step and 2-step processes) were introduced. 1-step refilling methods employed specially designed welding tools. The pin and shoulder (or sleeve) can be separately driven to stir the base material and refill the keyhole. In the 2-step refilling methods, friction stir and resistance spot processes were suggested as a successive process and optionally filler metal was supplied. Resistance spot process is more economical process than friction stir welding, and the keyhole was refilled without melting by selecting proper parameters.